The present invention relates to a rotary cutting apparatus for cutting an advancing web of sheet material. More particularly, the present invention is related to an adjustable rotary cutting apparatus for cutting serially connected envelope blanks from a web of sheet material advancing longitudinally through the cutting apparatus.
It is a common practice to manufacture envelopes by cutting envelope blanks in serially connected relationship from a web of sheet material, usually a high quality paper. The web is pulled from a spool and advanced or fed longitudinally through a cutting machine which removes corresponding sections from each side of the web. The knives in the cutting apparatus of the machine are so shaped that the material remaining in the web defines a series of interconnected envelope blanks, each blank having a front panel, two side flaps, a rear panel and a closing flap. The serially connected blanks are subsequently severed from one another by a cut-off knife. Each blank is then folded, pasted and gummed in addition to any other special processing required to form a finished envelope.
The cutting apparatus used in the past at each side of the advancing web of sheet material to form the serially connected envelope blanks has generally included a rotary knife cyclically engaging a stationary knife to shear a section conforming generally to one side flap and portions of the closing flap and the rear panel of the envelope. The cutting edges of the knives would, accordingly, have profiles corresponding precisely with the section of sheet material to be removed from one side of the web. If the size of the envelope was changed in such a manner that it necessitated a change in the shape of the envelope blank along a dimension extending parallel to the direction in which the web was fed through the cutting apparatus, it was necessary to change the rotary knife and stationary knife as well as the advancement of the web through the cutting apparatus during each knife rotation.
To cut different sized envelopes, therefore, it was necessary to have pairs of stationary and rotary knives of different sizes. Both sets of knives at each side of the web were replaced in their entirety whenever a different size of envelope was run.
It is an object of the present invention to disclose a new rotary cutting apparatus in which a single set of knives can be adjusted to cut envelopes of many different sizes.